time graph that you can use to make estimates. m s" + □" and this is plotted in the accompanying position vs. m g = w Extra credit (2 points): Find the total time of flight. 0 = 5000 m + &400 m s + □ − 1 2 □ □% □ = 92 s (5 points) Sketch a free body diagram for the rocket when it is at a height of 6 km and still ascending to its maximum height. 0 = &400 m s + % − 2 □ (□ − 5000 m) □ = 13 km (10 points) Find the time from engine shutdown to impact with the earth. &400 m s + % = 0 + 2 □ (5000 m − 0) □ = 16 m s% (10 points) Find the maximum height (with respect to the ground) the rocket achieves. (10 points) Find the average acceleration due to the rocket firing from ground to engine shutdown. Approximate the weight of the rocket to be constant. The rocket eventually crashes to earth at the same height as at takeoff. = −30 m □# 82 √ 30 s 9 = −120 m □& 82 √ 30 s 9 = −165 m □# − □& = 45 m A B Problem 2 (35 points) A single stage rocket takes off from the ground and fires until the rocket reaches an upwards velocity of 400 m/s at a height of 5 km. d) Extra credit (5 points) – Calculate the distance apart between the cars at twice the time of the overtake calculated in Part a. t plot for the Car B on the graph carefully noting the point of overtake. t plot for the Car A is sketched on the graph. b) (12 points) Calculate the x-coordinate where Car B will overtake Car A. Take the cars as point objects that are on parallel tracks so they won’t collide. a) (13 points) Calculate the time when Car B will overtake Car A. At t = 0, Car A is at x = 0 and begins to accelerate at -2 m/s 2 (to the left) while Car B is at x = 15 m and begins to accelerate at -3 m/s 2 (to the left). 7 s − 2 s = −130 m − 30 m 7 s − 2 s = −33 m s □□ □□ (4 s) = 0 Problem 1 (35 points) Car A and Car B are initially at rest. (5 points) The average velocity between 2 s and 7 s is about Choose answer: B (a) -65 m/s (b) -33 m/s (c) 0 m/s (d) 33 m/s (e) 65 m/s (5 points) The instantaneous velocity at t = 4 s is about Choose answer: C (a) -2 m/s (b) -1 m/s (c) 0 m/s (d) 1 m/s (e) 2 m/s □0-1 = □2.+ − □+. There are three multiple choice questions and two problems some with extra credit opportunities. PHYS 101 - Fall 2022-2023 - MIDTERM 1 – 10/19/ Name: _ Recitation section: _ 1 solutions to written problems must have adequate detail, and the answers must contain appropriate units to get full credit.
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